A significant amount of research has been directed both to the direct and indirect stimulation of nerves including the left and right vagus nerves, the sympathetic and parasympathetic nerves, the phrenic nerve, the sacral nerve, and the cavernous nerve to treat a wide variety of medical, psychiatric, and neurological disorders or conditions. More recently, stimulation of the vagus nerve has been proposed as a method for treating various heart conditions, including heart failure. Heart failure is a cardiac condition characterized by a deficiency in the ability of the heart to pump blood throughout the body and high filling pressure causing pulmonary fluid to build up in the lungs.
Typically, nerve stimulating electrodes are cuff- or impalement-type electrodes placed in direct contact with the nerve to be stimulated. These electrodes require surgical implantation and can cause irreversible nerve damage due to swelling or direct mechanical damage to the nerve. A less invasive approach is to stimulate the nerve through an adjacent vessel using an intravascular lead. A lead including one or more electrodes is inserted into a patient's vasculature and delivered to a site within a vessel adjacent a nerve to be stimulated.
Intravascular leads can be implanted using an over-the-wire technique where the lead includes a lumen extending the length of the lead and the lead is advanced over a guidewire to the desired location in the vein. Current over-the-wire leads, however, have lumens extending the length of the lead. This requires threading of the entire lead over the wire and results in a larger than desirable lead diameter. Furthermore, the lead generally travels an extensive distance through the vasculature, which requires navigability and flexibility of the lead. Thus, there is a need in the art for an intravascular medical electrical lead that can be implanted using an over-the-wire technique, yet does not require a lumen extending the length of the lead. There is also a need in the art for a lead that can be delivered directly to a desired location in the vasculature.